Annual costs resulting from medical expenses and lost productivity due to tobacco-related disease, disability, and death, areestimated at more than $150 billion. Despite the clear economic burden of tobacco on the health care system and the availability of proven treatments for tobacco dependence, many insurance programs and health plans in the United States do not offer a comprehensive benefit for these treatments. Health insurers and health care systems seek a 'business case' for investment in cessation treatment. This study wilt contribute new data on the impacts of cessation on health care utilization and costs of smokers quitting and not quitting within a large network of primary care clinics. A unique feature of the research is the longitudinal examination of health care utilization and costs for smokers actively recruited during routine primary care visits to receive pharmacotherapy and psychosocial cessation treatment. The specific aims of this study are to: (1) Obtain longitudinal data on health care utilization from the cohort of 1320 smokers participating in the Effectiveness study and from a sample of 633 continuing smokers identified through electronic medical record review who have not been recruited into a treatment-outcome study, (2) Using quit dates of protracted abstainers in the effectiveness study as reference points, compare health care utilization and costs among quitters and continuing smokers in the effectiveness trial cohort for two years prior to cessation and up to three and a half years post-cessation, (3) Using quit dates of protracted abstainers as reference points, compare types of health care visits and diagnoses among quitters and continuing smokers in the effectiveness study, and (4) Using data from the effectiveness study quitters (Cases) and the comparison group of patients who are continuing smokers (Controls), model the health care costs and utilization of quitters against their predicted costs had they not quit as determined from controls.